Patent GB-693553-A (GB)
Title: Filter aid feeder
IPC: C02F1/68
Filed: 1948-04-26
Abstract: 693,553. Feeding filter aids. DEHN, S. G. [Bowser, Inc.]. April 26, 1948, No. 11403/48. Class 46 [Also in Groups II and XXIX] A filter aid feeder includes a tank connected in a bypass of a flow-line for unfiltered liquid, the tank inlet being connected, above the bottom of the tank, with a jet-forming device comprising a chamber provided with radially-directed side wall portions having jet openings in them, the jet openings being disposed above the horizontal plane through the lower opening of a inverted frusto-conical filter-aid-supporting baffle within which a spreader is located in such a position as to form an annular opening with the lower portion of the baffle, so that tangentiallydirected jets of liquid from the jet openings create a swirl, causing dislodgment of filter aid from the baffle in the annular opening, and transfer of filter aid through the tank outlet to the flow line. A tank 1, Fig. 1, has a conical bottom 3 resting on a circular flange 66, Fig. 2, of a manifold 5 providing an inlet and an outlet and arranged in a by-pass 171, 187, Fig. 3, of a flow-line 126. A restriction constituted by a back-pressure valve 133, (see Group XXIX), located in the flow line 126 between the by-pass connections 149 and 193 induces flow into the by-pass and thence into the inlet. A feeding assembly, Fig. 2, rests on a flange 67 on the inlet channel 61 and comprises three parts: an inverted frustoconical baffle 107 for supporting filter aid and having a gasket 111 around its upper edge which makes contact with the conical bottom 3 of the tank; a liquid-jet-forming device 75, Fig. 6, comprising a neck 77, a chamber 81 and a bottom wall 87 terminating in a upturned rim 89; and a conical spreader 113 open at the bottom, Fig. 2. The jet-forming device 75 is secured at its rim to the baffle 107, and the chamber 81 has radially-extending portions 93 of its side wall each having an opening 95. The spreader 113 has a down-turned flange 115, an inwardly-extending projection 117 resting on the top wall 85 of the device 75 and a hole 119 through which extends a rod 121 having a collar 123 secured to it. The rod 121 screws at its lower end into a boss 103 on the device 75 to secure the spreader 113 to it. The feeding assembly may thus be lifted from or lowered on to the flange 67 by a :handle 125 at the top of the rod 121 which extends upwards into the tank 1. In operation a pump, (not shown), feeds liquid from the right of Fig. 3, some of it passing through valves 173, Fig. 3, and 161 on pipe 154, Fig. 1, valves 185, Fig. 3, and 207 on pipe 196, Fig. 1, being closed. The tank is filled to the level of a sight-glass 9, Fig..1, whereupon the pump is stopped. The tank is next filled with diatomaceous earth to a level below flange 169 and the cover 31 put on. With the vent valve 55 open the pump is again started and liquid fed until it issues from the vent which is thereupon closed. For precoating the filter, (not shown), valve 161 is left open and valves 173 and 185 are opened wide. Liquid flowing through the flow line 126 sets up a differential pressure across the valve 133 so that liquid is forced up pipe 154 and into tank 1, Fig. 1, and washes powder along spreader 113 and baffle 107, out over the rim 89, into the outlet space of the manifold 5 through the outlet and along the by-pass connection 193, Fig. 3, into the flow line. When precoating is complete valve 161 is closed and valve 173 regulated to give the proper powder feed indicated by pointer 291 and scale 293, Fig. 1. Filter aid is now fed solely by the assembly shown in Fig. 2. Liquid entering chamber 81 by the inlet 61 and 77 issues from holes 95 as tangential jets which wash powder down between spreader 113 and baffle 107 and discharge it across bottom wall 87 and over rim 89 into the space 68, whence it reaches the flow line 126. The rate of flow through the openings 95, and hence the rate of powder feed, may be varied by adjusting the spring loading of the valve 133, which adjustment varies the differential pressure across the valve.